1. Field of the Invention
This invention relates in general to devices used in the machining industry for holding and precision positioning of workpieces and more particularly to a multi-purpose angle plate apparatus having a precisely adjustable workpiece holder.
2. Description of the Prior Art
Various devices are used by the machining industry for holding and precision positioning of workpieces relative to machine tools, grind stones, and the like. Among such devices is the well known angle plate which basically includes two integrally formed plates disposed at a right angle with respect to each other. The primary intended usage of such angle plates, in so far as workpiece holding and positioning is concerned, is for flat placement of one of the plates on a supporting surface and mounting of a workpiece directly on the other upstanding plate. Angle plates are highly precision structures with regards to the angular relationship of the two plates, squareness and parallelism of the side and the edge surfaces and the like, and this allows them to be positioned in various attitudes in addition to the basic position discussed briefly above. Some of these variously configured angle plates are provide with V-grooves in the end surface of one, or both, or the plates, with the V-shaped grooves being provided for clamped attachment of workpieces therein. When workpieces are mounted in the V-grooves and the angle plate is supported in the basic position discussed above, on a support surface, such as the workbed of a machine tool, the workpiece is supported in a parallel relationship with respect to the support surface. If desired, the angle plate may be turned on its side, e.g. the adjacent side edges of the plates are resting on the support surface. In this attitude, a workpiece mounted in the V-grooves of the angle plates will be supportingly carried in a perpendicular relationship with respect to the support surface.
Therefore, angle plates of the basic type described above while being useful for their intended purpose are limited. For example, vertical adjustment of the workpieces relative to the support surface is possible, but is limited to the amount of vertical movement available, if any, within the V-groove when the angle plate is placed on its side. Further, such angle plates make no provision for adjusting and supporting workpieces in an angular attitude. A workpiece can be clamped in a desired angular attitude to the upstanding plate, but the angular adjustment must be made by some other instrument or device. This, of course, is a time consuming set-up of questionable accuracy and definitely does not lend itself to repeatability as needed in a production environment.
U.S. Pat. No. 3,824,744 discloses an angle plate structure which is designed to increase the versatility of such structures and thus overcome some of the shortcomings of basic angle plates. This prior art angle plate is provided with a right angle web in addition to the right angle plates and the web legs are provided with V-shaped grooves therein, and those V-shaped grooves are primarily intended for clamped attachment of workpieces therein. In addition, the two right angle plates are provided with transverse V-shaped grooves therein and an elongated V-shaped groove in the end edge of one of the plates. All of those V-shaped grooves, that is, the one provided in the plates and the web may be used for positioning the angle plate in an angular attitude relative to a support surface. This is accomplished by placing dowels in two of the V-grooves which lie in the same plane. One of the dowels is placed in direct bearing engagement with the support surface and the other is shimmed relative to that surface with a block or blocks of known dimension. This is a technique commonly used in the machining arts for precision setting of what are commonly referred to as sine bars or sine plates. Briefly, the distance between the two dowels is known and the dimension of the shim or shims is also know. With those two knowns, the angular relationship between the support surface and the surface containing the V-grooves in which the dowels are mounted can be calculated using a known trigonometric formula, or by simply using sine tables that are usually available in machine shops.
From the above, it will be seen that this particular prior art angle plate, in effect, becomes a sine plate when used in the manner described above. However, when so used, it is sometimes difficult if not impossible to bolt, clamp or otherwise attach the angle plate to the work surface, with the degree of difficulty increasing when relatively large angles are involved.
In addition, this prior art angle plate is provided with a plurality of precisely located holes in one of the plates for selective placement of a pair of dowels therein. The dowels are positionable in predetermined angular relationships and shim blocks can be employed in conjunction therewith for setting other angular relationships and a sine bar is supported on the dowels. When the sine bar is adjusted in this manner, a workpiece is supported on the upper surface of the sine bar and is clamped to the adjacent surface of the angle plate. Even though this prior art angle plate is provided with this latter sine bar workpiece adjusting capability, it is limited as to its ability for precision holding of workpieces relative to the sine bar in that the workpiece is clampingly attached to the angle plate rather than directly to the sine bar. For example, cylindrical, and relatively small, workpieces cannot be accurately positioned relative to such a structure and accurate repeatable workpiece positioning for production purposes in difficult, if not impossible. Additionally, some workpieces cannot be held at all in this manner due to the interference with the adjacent angle plate.
Therefore, a need exists for a new and improved angle plate apparatus with precisely adjustable workpiece holder which overcomes some of the problems and shortcomings of the prior art.